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Sun Aug 3 20:53:54 2008
We got our repaired Guralp back in the mail from England (s/n T4157). I plugged it in
to Ben's 3-Guralp breakout box (
verified that it is not oscillating (like it was before) and that it responds to us
The breakout box has way too much gain, however. The ADC wants +/-2 V and the box puts out
~5 Vpk in the night time.
Looking at the schematic, it has a DC gain of 200 and a double whitener (50,50:10,10) so that
there's a gain of 5000 from 50-2000 Hz. The Guralp has a transduction gain of 800 V/(m/s) and
so we can just calculate what the frequency dependent noise figure of the box has to be. I've
pulled it out, put it on the bench, and started reworking it. I am looking for a soldering/
The other kink in the problem is that since we want to use this for the adaptive noise cancellation,
we have to make the noise floor of the readout better than the ambient noise by the same factor
with which we want to cancel the noise.